Cover for chip carrier socket

ABSTRACT

a cover assembly for a leadless chip carrier socket including a spring cover and locking bracket selectively positionable on a socket body in any one of four positions. The spring cover is pivotally mounted on the socket body and is movable between an open position and a closed position at which the cover engages the locking bracket. The cover is formed with four arm members which are spring loaded and which engage the top of a chip carrier at eight pressure points. The force exerted by the spring cover in a closed position applies a downward force against the chip package to effect positive electrical contact with a plurality of contacts mounted in the socket which are adapted to be interconnected with a printed circuit board or circuit pad.

BACKGROUND OF THE INVENTION

This invention relates in general to electrical connectors and, inparticular, to a socket for a leadless chip carrier or package.

More specifically, the invention relates to an improved cover assemblyand locking bracket selectively attachable to a chip carrier socket atany one of four positions as required in various applications. The coverassembly is provided with means to apply a force to a chip carrierwithin a carrier socket for uniform and positive connection with thecontact means therein.

In many electrical circuit designs, a leadless, semiconductive chippackage is interconnected with a printed circuit board or circuit pad bymeans of a carrier socket. Carrier sockets of this type conventionallyinclude a base receptacle in which the circuit package is inserted forinterconnection with a pad. The base receptacle of a socket is providedwith an upper access opening to permit insertion and removal of the chipcarrier from the socket as needed. A cover assembly is typically mountedon the socket in association with the access opening to engage the chipcarrier and, when closed, applies a force on the chip body and biases itagainst the contacts of the carrier socket. In some prior designs, thechip is depressed downward in a manner that it is resiliently capturedbetween yieldable members. The "floating" effect of such priortechniques does not provide a desirable degree of positive and uniformcontact between the carrier and the plurality of contacts arranged within the socket carrier. In addition, it is advantageous that the forceexerted on the chip package by the cover not only be discretely appliedto protect the components, but also be of a sufficient magnitude toattain a positive connection with the number of contacts within thesocket. Prior designs in general have not functioned in a manner toapply a distributed force against the chip package to attain a uniformand effective connection with the socket contacts, while protecting thecomponents.

Because a carrier socket may be employed in a wide range ofapplications, many prior cover assemblies are also disadvantageouslylimited to one, or perhaps two, attachment positions on the socket. Thecarrier socket is a polarized component as is the chip carrier itself.Because the chip carrier must then be properly aligned in the socket andthe socket must be appropriately oriented on the board, such limitationsof the relative positioning of the elements can be inconvenient to theuser, since physical conditions may not permit opening or closing of thecover in the limited direction dictated by prior designs.

Many prior carrier sockets suffer from other shortcomings whichinterfere with their effectiveness and convenience of use. A coverassembly, for example, applies a significant force to the chip carrier,and must be locked by an effective mechanism capable of being easilylocked and unlocked with a minimal force being applied to thecomponents. Locking techniques in the past fail to incorporate both thecharacteristics of ease of use with effectiveness of locking andprotection to the elements. In addition, known sockets do not offer asimple and inexpensive technique by which the cover assembly and/orlatch may be electrically grounded, a consideration to avoid cross-talkbetween contacts, particularly a problem in high speed functions.

In view of the foregoing shortcomings of known techniques and otherproblems not specifically enumerated, a significant need exists for animproved cover assembly and locking means for a chip carrier socketcapable of overcoming many of the problems associated with the priorart.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide an improvedcover assembly and locking bracket for a chip carrier socket.

Another object of this invention is to improve the application of forcebeing exerted by a cover assembly against a chip carrier within asocket.

A further object of this invention is to provide a cover assemblycapable of being attached to a chip carrier socket at a plurality ofselected positions.

Still another object of this invention is to provide an improved lockingbracket to minimize the application of force to a chip carrier socketduring latching and unlatching operations.

A still further object of the invention is to provide an effectivedevice for electrically grounding the cover assembly and locking bracketof a chip carrier socket.

These and other objects are attached in accordance with the presentinvention wherein there is provided an improved cover assembly andlatching bracket for a chip carrier socket that is capable of beingconnected to a printed circuit board or circuit pad by any well-knowntechnique, such as, for example, by soldering or pressure contact. Thecover assembly herein disclosed includes a plurality of resilientlymounted arm members to apply a downward force to a chip carrier at aplurality of discrete points for uniform mechanical and electricalcontact with the contact means of the socket receptacle. The coverassembly and associated locking bracket of the invention may beselectively attached to the socket at any one of four positions to allowthe user to choose the direction in which the cover opens.

DESCRIPTION OF THE DRAWINGS

Further objects of the invention together with additional featurescontributing thereto and advantages accruing therefrom will be apparentfrom the following description of preferred embodiments of theinvention, which are shown in the accompanying drawings with likereference numerals indicating corresponding parts throughout wherein:

FIG. 1 is a side perspective view of the improved cover and lockingbracket of the invention shown in an open configuration on a leadlesschip carrier socket;

FIG. 2 is a top schematic view of the locking bracket of FIG. 1;

FIG. 3 is a back schematic view, with parts in section, taken along line3--3 of FIG. 2;

FIG. 4 is an end schematic view of the locking bracket of FIG. 2;

FIG. 5 is a top schematic view of the cover assembly of FIG. 1;

FIG. 6 is an end schematic view of the cover of assembly of FIG. 5;

FIG. 7 is a side schematic view of the cover assembly of FIG. 5;

FIG. 8 is a top schematic view, with parts cut away of improved coverassembly and latching bracket of FIG. 1, in a closed configuration;

FIG. 9 is a side schematic view, with parts in section, taken along 9--9of FIG. 8;

FIG. 10 is a top schematic view of the electrical grounding lug of theinvention;

FIG. 11 is a front schematic view of the electrical grounding lug ofFIG. 10; and

FIG. 12 is a side schematic view of the electrical grounding lug of FIG.10.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to FIG. 1 there is illustrated a chip carrier socket 2having the improved cover assembly 4 and locking bracket 6 of theinvention. The chip carrier socket 2 acts as a connector through which asemi-conductive chip carrier or package 3 mounted therein is connectedto a printed circuit panel or circuit pad (not shown). Although thecover assembly and locking bracket herein disclosed may be equally usedwith other carrier sockets, such as the well-known pressure or surfacecompression type and the like, the chip carrier socket 2 is shown asbeing of a solder type design which will be apparent from the followingdiscussion.

The chip carrier socket 2 forms an upwardly opening receptacle 10 havinga rectangular configuration defined by enlarged corner sections or posts11 interconnected by four upright side walls 12 and a bottom wall 13.The socket 2 may be constructed from a suitable molded material and thelike such as, for example, an electrically insulative plastic material.An upward facing shoulder or ledge 14 is formed on all four sides withinthe square receptacle 10 around its outer periphery or edge. As bestshown in FIG. 1, side walls 12 include a continuous upper portion 15 anda lower plurality of parallel plate-like sections 16. The areas 16abetween the plates 16 form contact compartments which open at the bottomand outside of the socket body and open in receptacle 10 throughapertures 17 disposed in upper portion 15 immediately above ledge 14.

A plurality of apertures 18 are further provided through ledge 14 inopen alignment with apertures 17. Apertures 17 and 18 provide openingsthrough which a portion of the carrier socket may establish mechanicaland electrical contact with a chip carrier. A leadless chip carrier orpackage 3 (partially shown in FIGS. 8 and 9), generally comprising aconventional semi-conductor chip circuit mounted on a substrate andsuitable for micro processing applications and the like, is adapted tobe positioned within the receptacle 10 to effect electrical andmechanical contact between the peripheral edges of the chip package anda plurality of electrically conductive contacts 20.

Although the cover assembly and locking bracket of the invention may beused in other chip carrier sockets, such as a compression type and thelike, and with other specific contact designs other than hereindisclosed, in FIGS. 1 and 9 two types of contacts 20a and 20b, formedfrom a conductive elongated material in the form of a metal are shown.Contacts 20a and 20b extend vertically from a position adjacentapertures 17 and 18 and terminate at exterior terminal ends forattachment to the circuit by soldering. The contacts 20a and 20b arevertically separated from each other by the plurality of verticalsections 16 forming a portion of side walls 12 as best shown in FIGS. 1and 9.

The rectangular array of terminal pins 34a and 34b are adapted to passthrough pin apertures in a pad (not shown). The solder tails thereof arethen soldered to the underside of the pad having a suitable circuitry,sometimes known as a foot print, to effect an electrical connectiontherebetween. In many pads a foot print is positioned on both sides ofthe panel.

Each of the corner posts 11 of the carrier socket includes a pair ormounting holes 50 on its outer surfaces, providing two holes at each endof the four sides of the socket. One of the corners 52 of the receptacle10 possesses a beveled shape in the vertical section above ledge 14, asopposed to an approximate square configuration at the other threecorners 54. This corner arrangement insures that the chip carrier isproperly aligned within the socket during insertion, since bothcomponents are normally polarized.

Referring now to FIGS. 1, 2, 3 and 4 the cover locking bracket 6 is bestillustrated. The locking bracket 6 may be formed from a metal materialand the like and includes a pair of opposite, downwardly extendingsupport arms 60 on which inwardly projecting hollow bosses 62 areformed. Pivots 62 have an outer configuration to match the holes 50 andare adapted to be inserted in opposite aligned holes 50. The pivots 62are capable of being releasably snapped into and from position thereinas desired by limited deformation of the arms 60. The spaced arms 60 areinterconnected by a cross member 66 having enlarged end portions 68,which are integrally attached to a respective arm 60. The cross member66 may be formed with a strengthening rib 70 as best shown in FIGS. 2and 3.

The outer edge 66a of cross member 66 is designed to project slightlybeyond the outer surface of the socket to permit a latching structure 72to integrally depend downwardly therefrom and then upwardly above thesocket. The latching assembly 72 includes a pair of lock bar supportarms 74 comprising a pair of lower segments 76 formed by bending backtwo segments as a double thickness, and a pair of upper sections 78projecting therefrom above the cross member 66. An elongated element orbar 80 integrally connects the pair of the lock bar support arms 74. Asshown in FIG. 3, the upper edge portion of latching assembly 72 curvesoutwardly to form a cam surface 82 for cooperative action with the coverassembly 4 as will be described. It should be apparent that the lockingbracket 6 (FIG. 4) is capable of only limited pivotal movement in adirection radial of the center of the socket, because of the closeproximity of segments 76 of the latching structure 72 and the carriersocket.

Referring now to FIGS. 5, 6 and 7, details of the cover assembly 4 arebest illustrated. The cover assembly 4 includes a four sided rectangularframe 92 created by four interconnected sides 92a that define a centralopening 92b. A pair of side panels 94 integrally depend downwardly froman opposite pair of frame sections 92a and are provided with a pair ofcover pivot arms 96 adjacent one side of the cover frame 92 as bestshown in FIGS. 1 and 7. The side panels 94 are disposed adjacent theouter surface of socket side walls 12 in a closed configuration of thecover assembly as partially illustrated in FIG. 9. An inwardlyprojecting pivot 98 is formed on each of the cover pivot arms 96 and isof the same design as the pivot members 62 of the locking bracket 6. Thepivot members 98 are adapted to be releasably inserted in a aligned pairof holes 50 on opposite sides of the carrier socket body, and at theopposite side of the socket from the mounting of the latching bracket 6.Thus, the locking bracket 6 and cover assembly 4 may be selectivelymounted in any one of four separate positions on the carrier socket 2.Such versatility of mounting thus permits the cover to open in any oneof four different directions as may be necessary or desirable innumerous application.

A continuous rib 100 is provided around the four sections 92a of thecover frame 92. The cover frame 92 is further strengthened by beveledareas 102 disposed at each of the corners interconnecting the four coverframe sections. A locking lip 104 projects outward from the particularframe section 92a, which is situated opposite to the mounting of thecover pivot arms, and is designed to engage the underside of the lockingbar 60 in a locked configuration. Locking engagement is automaticallyeffected during closing of the cover assembly by contact of the lip 104with the cam surface 82 of the locking bracket 6 to pivot it outward.Release of the cover is simply accomplished by manually moving thelocking bracket away from the engaged position of the lip 104 underlocking bar 60.

Four spring members on brackets 110 symmetrically project into thecentral opening 92b within the four sections of the cover frame 92. Eachof the spring brackets 110 comprises a pair of curved resilient springmembers 112, which function as cantilever beams or arms, and arecentrally supported on a cover frame 92a by a base projection 114. Thespring members 112 of each spring bracket 110 bend downward from thebase 114 in opposite directions as best shown in FIG. 6 and terminate ata free end portion 116 at which end of the spring members applies aresilient force to a chip carrier mounted in the socket receptacle 10upon closing and locking of the cover assembly 4.

When a chip carrier is inserted into the socket receptacle 10 and thecover assembly is closed and locked as shown in FIGS. 8 and 9, the coverassembly applies a downward force on the back of the chip at eightpoints of contact about a common center. This symmetrically appliedforce is greater than the total force generated on the bottom of thechip carrier by the plurality of contacts 24a and 24b protruding aboveshoulder 14. According, the contacts 24a and 24b are resilientlydepressed and the chip carrier is caused to press directly against theshoulder 14 to attain an efficient mechanical and electrical connectionwith the contacts. This cooperative action further insures that thecontacts 20a and 20b are not mechanically overloaded. It should be alsonoted that the cover assembly is capable of accommodating a heat sinkextending up from the back side of chip carrier as needed in certainapplications. Because a heat sink can project upward beyond the socketand cover, actual pivotal movement of the cover is then impeded. Thisproblem is avoided in the present invention, because the cover assembly4 can be vertically moved relative to the heat sink to be snapped intoposition on the socket body or removed in the opposite manner.

The chip carrier socket herein disclosed is also capable of electricallygrounding the cover assembly 4 or the locking brackets 6, or bothcomponents, with conductive metal lugs 130. Four separate lugs 130 arerequired to ground both the cover assembly and locking bracket, but onlytwo lugs 130 are employed in the socket illustrated in FIGS. 1, 8 and 9to ground the cover assembly. The lugs 130 include a flat upper bodyportion 132 which mounts beneath the pivot arms 96 of the cover assembly4, or alternatively beneath support arms 60 of the locking bracket 6, ifthat component is grounded. The body 132 is integrally connected to alower projection 134 adapted to be inserted into the ground hole (notshown) formed through socket body 2 for connection to a groundingcircuit. To effect proper alignment of the lower projection 134 with thesocket ground hole, projection 134 is disposed inward of the lug body132 through an intermediate integral section 136, as best shown in FIG.12.

The lug body 132 is constructed with central opening 138, allowing thepivot bosses 98 of the cover assembly, or of the locking bracket, toproject through opening 138 into a socket hole 50. An upper projection140 extends at an approximate right angle to the lug body at the upperedge of opening 138 for insertion into holes 50 in contact with thepivots of the cover assembly or locking bracket. The vertical height ofthe opening 138 is selected to be of a magnitude to cause the pivotbosses 62 or 98 to engage the lug body at projection 140, while thepivot members 62 and 98 are snapped into place in holes 50. Accordingly,electrical contact between the cover assembly 4, or the locking bracket6, and lug 130 is effected to ground either of the components throughthe lug body to a grounding circuit.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapted a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodimentsdisclosed as the best mode contemplated for carrying out this invention,but that the invention will include all embodiments falling within thescope of the appended claims.

What is claimed is:
 1. A chip carrier socket comprising:receptacle meanshaving a plurality of electrical contacts adapted to be interconnectedwith an electrical circuit; said receptacle means forming a rectangularreceptacle having an upper access opening for receiving a leadless chipcarrier for connection with the electrical circuit; said receptaclemeans further forming an upwardly facing surface within said receptaclefor engaging a portion of the chip carrier element inserted therein;said receptacle means further including means for creating an electricalconnection between a portion of said plurality of electrical contactsand the active chip carrier in engagement with said surface; cover meanshaving four intersecting sides being pivotally mounted on saidreceptacle means for movement between an open position and a closedposition over said upper opening to said receptacle; bracket meansmounted on said receptacle means for locking said cover means in saidclosed position and for releasing said cover means from said closedposition; said cover means having a plurality of resilient springmembers to apply a force to the chip carrier in said closed position;said plurality of spring members acting to apply a force at plurality ofdiscrete points to press the chip carrier in positive contact with saidreceptacle surface in electrical contact with said portion of saidelectrical contacts; said spring members are in the form of a pluralityof resilient cantilevered arms; said plurality of cantilevered armscurve downward into said receptacle from said cover means to apply aforce to the chip carrier within the receptacle at their respective freeends; said plurality of cantilevered arms are arranged as separate pairsof arms, a base projection being carried at an intermediate portion ofeach of said four sides, each of said pairs being supported by arespective one of said base projections and being positionedsymmetrically on said cover means with the free ends of said pairextending in opposite directions from said base projection to contactthe chip carrier at discrete points and apply a force thereto about acommon center.
 2. The chip carrier socket according to claim 1 whereinsaid portion of said electrical contacts extend upward be yond saidsurface in absence of a chip carrier within said receptacle.
 3. The chipcarrier socket according to claim 2 wherein said portions of saidelectrical contacts are resiliently deformed in contact with the chipcarrier by the force exerted by said cover means in said closedposition.
 4. The chip carrier socket according to claim 3 wherein theforce exerted by said cover means on the chip carrier is greater thanthe force exerted thereon by said plurality of contacts.
 5. The chipcarrier socket according to claim 1 further including means toelectrically ground said cover means and said locking bracket means. 6.The chip carrier socket according to claim 5 wherein said electricalground means includes at least one pair of conductive lug members inelectrical contact with either one or both of said cover means and saidbracket means.
 7. A cover assembly and locking bracket for a chipcarrier socket comprising:cover means adapted to be mounted adjacent anupper access opening of a chip carrier socket; said cover means having acover member formed by a continuous frame portion having four sides anddefining a central opening in said cover member; a pair of pivot armsfor mounting said cover member on the carrier socket for pivotalmovement between an open and closed position; said cover member having aplurality of cantilevered spring members depending therefrom and adaptedto extend into the access opening to a position beneath said covermember; a base portion carried by each of said four sides at anintermediate position thereof, and each of said base portions supportinga pair of cantilevered spring members having free ends disposed inopposite directions therefrom, the free ends of each pair ofcantilevered arms arranged to contact the chip carrier at two discretepoints in a closed position of said cover member; said spring membersarranged to apply a force to a chip carrier positioned in the socket insaid closed position of said cover member; and a locking bracket adaptedto be mounted on the carrier socket and arranged for limited movementfor engaging a portion of said cover member for the locking thereof insaid closed position and for releasing said cover member from saidclosed position.
 8. The cover assembly and locking bracket of claim 7wherein said base portions extend from each of said four sides into saidcover opening.
 9. The cover assembly and locking bracket according toclaim 7 wherein said locking bracket is pivotally movable in a directionextending radially outward from the center of said cover member tominimize the forces applied thereto during locking and unlocking. 10.The cover assembly and locking bracket according to claim 7 furthercomprising at least one pair of electrically conductive lug members toground at least either of said cover member or said locking bracket,said lug members being mounted in electrical contact with a portion ofsaid cover member or said locking bracket.
 11. The cover assembly andlocking bracket according to claim 10 wherein each of said lug membersincludes a respective opening through which a portion of either saidcover means or said locking bracket extends.
 12. The cover assembly andlocking bracket according to claim 10 wherein each of said lug membersincludes a projecting member extending into the socket in contact with aportion of the cover means or said locking bracket.
 13. The coverassembly and locking bracket according to claim 7 wherein said centralopening is arranged between said spring members to permit a heat sinkassociated with the chip carrier to protrude upward through said centralopening.
 14. The cover assembly and locking bracket according to claim13 further including means for selectively attaching and detaching thepivot arms from their mounting on said carrier socket to permit movementof said cover member between an open position and a closed position inthe presence of a heat sink.
 15. A chip carrier socketcomprising:receptacle means having a plurality of electrical contactsadapted to be interconnected with an electrical circuit; said receptaclemeans having a plurality of flat intersecting external walls formingfour corners and forming a receptacle having an upper access opening forreceiving a leadless chip carrier for connection with the electricalcircuit; said receptacle means further forming an upwardly facingsurface within said receptacle for engaging a portion of the chipcarrier element inserted therein; said receptacle means furtherincluding means for creating an electrical connection between a portionof said plurality of electrical contacts and the active chip carrier inengagement with said surface; cover means pivotally mounted in any oneof four positions on said receptacle means for movement between an openposition and a closed position over said upper opening to saidreceptacle; said cover means having a lip portion for locking said covermeans; bracket means mounted on said receptacle means to selectivelyengage said lip portion for locking said cover means in said closedposition and for releasing said cover means from said closed position;said cover means having a plurality of resilient spring members to applya force to the chip carrier in said closed position; said plurality ofspring members acting to apply a force at plurality of discrete pointsto press the chip carrier in positive contact with said receptaclesurface in electrical contact with said portion of said electricalcontacts; said bracket means being pivotally mounted on said receptaclemeans for locking and releasing said cover means; said bracket meansincluding a bar movable from a position above said lip portion inengagement therewith in closed position and movable away from said lipduring pivotal movement of said bracket means for releasing said covermeans; said receptacle having a plurality of holes on each side adjacenteach intersecting corner of said sides; said bracket means havinginsertion means for releasably engaging two holes respectively onselected opposed sides of said receptacle; said bar having integral armscarrying means to engage two of the other holes on said selected opposedsides.
 16. The chip carrier socket according to claim 15 wherein saidreceptacle means includes means for mounting said cover means and saidbracket means at one of a plurality of selected positions to permit saidcover means to move between said open and said closed position in one ofa plurality of directions.
 17. The chip carrier socket according toclaim 16 wherein said mounting means is arranged to mount said covermeans and said bracket means for pivotable movement at one of fourdiscrete positions.